1. Field of the Invention
The present invention relates to a vertical vibrator, and more particularly to an internal weight type vertical vibrator, in which a yoke surrounds a weight for increasing dimensions of a region, where a coil for current is interlinked with a magnetic field of a magnet, thereby improving vibrating efficiency and vibrating power.
2. Description of the Related Art
Generally, sound and vibration are used to inform users of an incoming call. A small-sized vibrating motor is driven to generate vibration, and driving force of the vibrating motor is transmitted to a housing of a device, thereby vibrating the whole portions of the device.
A vibrating motor, which is one incoming call notification means applied to a communication device, such as a cellular phone, converts electrical energy to mechanical energy using the principle of electromagnetic force, and is installed in a cellular phone for informing users of an incoming call without sound.
As the cellular phone market has been rapidly extending and cellular phones have grown to include many additional functions, components of the cellular phone are developed toward miniaturization and high quality. Accordingly, a vibrating motor having a novel structure, which solves drawbacks of the conventional vibrating motor and has an improved quality, are required now.
FIG. 1 is a cross-sectional view of a conventional coin type vibrating motor. The conventional coin type or flat type vibrating motor 1 comprises a stator 20, a rotor 10 installed rotatably against the stator 20, and a housing 30 accommodating the stator 20 and the rotor 10.
When external power is applied to the vibrating motor 1 through a pair of brushes 25 installed on a lower substrate 21 of the stator 20, currents having different polarities flow along the brushes 25. Since upper ends of the brushes 25 elastically contact a commutator 15 formed on the lower surface of the rotor 10, power is supplied to a wound coil 12 of the rotor 10 through the commutator 15 contacting the brushes 25.
The rotor 10 is rotated in one direction centering on a shaft 31 by interaction between an electric field formed by a direction of the flow of the current induced to the wound coil 12 and a magnetic field formed by a magnet 22 of the stator 20.
Here, contact points between the brushes 25 and segments of the commutator 15 contacting the brushes 25 vary whenever the rotor 10 is rotated, and the polarity of the power is continuously changed. Thereby, the rotor 10 having the eccentric center of gravity is continuously rotated, thus inducing vibration used as a signal expressing the notification of an incoming call.
In FIG. 1, non-described reference numeral 14 represents an insulator surrounding the wound coil 12 and a weight, non-described reference numeral 32 represents a bearing member, and non-described reference numeral 35 represents a base for closing the opened lower part of the housing 30.
The above vibrating motor 1 generates mechanical vibration by rotating the rotor 10 having a weight eccentrically disposed when external power is supplied to the vibrating motor 1. The rotating force of the rotor 10 is mainly embodied by a commutator or brush type structure of the motor, which supplies current to the coil of the rotor 10 by a commutating action through contact points between the brushes 25 and the commutator 15.
However, when the above-structured vibrating motor 1 is driven, the brushes 25 pass through a gap between segments of the commutator 15, thus causing mechanical friction and electrical sparks between the brushes 25 and the segments of the commutator 15 and abrasion of the brushes 25 and the commutator 15, thereby producing foreign substances, such as black powder and shortening the lifespan of the motor.
Accordingly, in order to solve the drawbacks of the conventional commutator or brush type vibrating motor, a multifunctional actuator, serving as means for inducing sound or vertical vibration using the resonant frequency of a vibrometer, has been developed.
FIG. 2 is a cross-sectional view of a conventional multifunctional actuator. As shown in FIG. 2, the actuator 2 comprises a main case 40 having an internal space, a vibrating plate 50 installed on the upper part of the main case 40 and provided with a sound-generating coil 52 generating sound according to a signal source, installed on the lower surface thereof, a magnet 60 vertically installed in the main case 40 and provided with an upper plate 62 mounted on the upper surface thereof for forming a magnetic circuit, the upper plate 62, a weight 65 constituting a vibrating body together with a yoke 64 mounting the magnet thereon, a plate spring 66 for elastically supporting the vibrating body in the main case 40, and a vibration-generating coil 42, placed just below the vibrating body, generating vibration.
In FIG. 2, non-described reference numeral 43 represents an upper case for closing the upper part of the main case 40, and non-described reference numeral 44 represents a base provided with the vibration-generating coil 42 mounted thereon.
The actuator 2 supplies external power to the sound-generating coil 52 or the vibration-generating coil 42 through a lead wire (not shown), thereby selectively generating sound and vibration. When power is supplied to the sound-generating coil 52, the vibrating plate 50 is finely vibrated by interaction between a magnetic field generated from a magnetic circuit constituted by the magnet 60, the upper plate 62 and the yoke 64 and an electric field generated from the sound-generating coil 52, thereby generating sound.
On the other hand, when power is supplied to the vibration-generating coil 42, the vibrating body, including the magnet 60, the upper plate 62, the yoke 64 and the weight 65, which is suspended by the plate spring 66, is vertically vibrated by interaction between the magnetic field generated from the magnetic circuit including the magnet 60, the upper plate 62 and the yoke 64 and an electric field generated from the vibration-generating coil 42.
Here, the vibrating degree of the vibrating body varies according to the intensity and frequency of a signal for generating the vibration. In case that vertical vibrating width of the vibrating body is larger than a predetermined value, the vibrating body contacts the sound-generating coil 52 serving as an upper structure or the vibration-generating coil 42 serving as a lower structure, thus generating a touch tone. For this reason, as shown in FIG. 2, magnetic bodies 70, serving as dampers for absorbing impact when the vibrating body contacts the lower structure, are placed on the lower surface of the yoke 64.
The actuator 2 requires a large number of components and has a complicated structure, thus limiting miniaturization and simplification of products and increasing production costs.
Accordingly, in order to solve the above problems of the actuator 2, a vertical vibrator 3, which requires a small number of components and generates vertical vibration, has been developed.
FIG. 3 is a cross-sectional view of a conventional vertical vibrator. As shown in FIG. 3, the conventional vertical vibrator 3 comprises a case 81 having an internal space with a designated volume, a magnet 82 vertically installed therein, spring members 86 installed between the housing 81 and a yoke 84 for vibrating a vibrating body, which includes the yoke 84 mounting the magnet 82 thereon and a weight 85 installed on the outer part of the yoke 84 and constitutes a magnetic circuit together with the magnet 82, and a vibration-generating coil 87 placed on the upper surface of a base 88 closing the lower part of the housing 81.
When power is supplied to the vibration-generating coil 87, a magnetic flux, which is the flow of a magnetic field (B) generated from the magnetic circuit constituted by the magnet 82 and the yoke 84, is leaked from the lower surface of the magnet 82 and interlinked with the vibration-generating coil 87, thereby forming a route flowing toward the lower end of the yoke 84. The vibrating body, which includes the magnet 82, the yoke 84 and the weight 85 and is suspended by the spring members 86 in the housing 81, is vertically vibrated by interaction between a magnetic field of the magnetic circuit and an electric field of the vibration-generating coil 87.
Since the yoke 84 of the conventional vertical vibrator 3 surrounds the external surface of the magnet 82 vertically installed in the vertical vibrator 3, the conventional vertical vibrator 3 has a reduced magnetic resistance. However, since there generates a route of the magnetic field (B) leaked from the magnet 82, which is not interlinked with the coil 87 but is lead into the lower end of the yoke 84, vibrating efficiency and vibrating power of the conventional vertical vibrator 3 are reduced.
Further, since only a central area of the coil 87 influenced by the magnetic field leaked from the magnet 83 of the overall diameter (d) of the coil 87 generates power for generating exciting force, the degree of freedom in designing the winding number of the coil 87 placed on the base 87 is reduced.